Known cutters for printed substrates generally comprise a supporting plane adapted to receive a printed substrate, as well as a plurality of cutting units comprising a blade having a substantially circular shape rotatably mounted about an axis parallel to the supporting plane. The cutting units are generally mounted on a cutter so as to make cuts along mutual orthogonal directions, in particular along a longitudinal direction parallel to a feeding direction of a substrate, and along a transverse direction perpendicular thereto.
The cutters also generally comprise cylinders suitable to drag the printed substrate along the supporting plane, so that the cuts needed to separate individual images printed on the substrate are obtained by way of relative movements between the substrate and the blades of the cutting units. In order to make cuts along the longitudinal direction, one or more longitudinal cutting units are used the blades of which are aligned along the feeding direction of the substrate. These cutting units are generally slidably restrained to a crosspiece of the cutter along suitable rails that allow adjustment of their relative positions, as well as their locking on the crosspiece. In order to make cuts along the transverse direction at least one transverse cutting unit is generally provided, the blade of which is aligned along the transverse direction. This cutting unit is transversely movable between the ends of the cutter by way of a suitable motorized slider.
In digital printing processes of substrates made of a rigid material, printed images are separated from each other by edges suitable to allow the cutting units described above to cut them. The edges are generally identified by special cutting marks, such as e.g. bar codes, that are automatically detectable via sensors, its particular optical sensors, which allow automatic cutting of printed substrates.
Since the width of the edges has a non-negligible size, the cutting operations necessary to cut the images printed from a substrate require to carry out for each edge a first and a second cut spaced according to the size of the edge to eliminate. In order to make a cut e.g. along the transverse direction, when the sensors detect a cutting mark the cutter cylinders are stopped, thus blocking the printed substrate for the execution of a first transverse cut. Subsequently, the cylinders cause the printed substrate to advance along a path the length of which corresponds to the width of the edge, then are stopped again to allow the execution of a second transverse cut.
This sequence of movements and stops of printed substrates results in cutting operations that are considered quite long by the those skilled in the art.
Another problem related to the execution of cuts in printed substrates is that after a cutting operation the edges separated from the images constitute scraps which move together with them and must be removed manually by an operator at the exit from the cutter, which is a time consuming operation.